Lyme disease, the most common tick-borne infection in the United States and Europe, is a multisystemic infection which is caused by the spirochete Borrelia burgdorferi and affects humans and many species of animals. Early diagnosis and intervention can effectively prevent the development of more serious clinical manifestations, but the currently used serological tests for Lyme are not very reliable indicators of early disease. During Phase I of this grant, we have developed a PCR based DNA capture assay for the direct detection of B. burgdorferi which may be a valuable adjunct to the current serological diagnostic tests and help control Lyme disease infections. In the course of Phase II, we propose to further refine this assay and demonstrate its usefulness in the diagnosis of Lyme disease in a clinical reference lab. Many of the difficulties of applying PCR technology to the diagnosis of Lyme disease, including sample selection and preparation, ability to identify various B. burgdorferi isolates, technical complexity of carrying out the assay, and control of false positives and false negatives will be addressed. The assay will be validated on a number of actual clinical samples from Lyme disease patients at various stages of the disease or following therapy.